Novel bacteriophage and antibacterial composition comprising the same

ABSTRACT

Provided is a novel bacteriophage ΦCJ20 (KCCM11362P). In addition, the present invention relates to an antibacterial composition including the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient. Further, the present invention is a method of preventing and/or treating infectious diseases by enterotoxigenic  Escherichia coli  in animals except for humans using the bacteriophage ΦCJ20 (KCCM11362P) or the antibacterial composition containing the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient.

TECHNICAL FIELD

The present invention relates to a novel bacteriophage having a specific bactericidal activity against Enterotoxigenic Escherichia coli (ETEC), and an antibacterial composition comprising the same. In addition, the present invention relates to a method of preventing or treating animal diseases using the novel bacteriophage or the antibacterial composition.

BACKGROUND ART

Escherichia coli (hereinafter referred to as ‘E. coli’) is a Gram-negative, short rod-shaped bacterium belonging to the genus Escherichia and the family Enterobacteriaceae, and is one of the normal flora existing in the intestines of various animals including mammals. It was known that most of the strains of E. coli are non-pathogenic and may cause opportunistic infections, but some highly pathogenic strains cause diverse intestinal diseases and sepsis in animals including humans.

An example of E. coli may include enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), enteroaggregative E. coli (EAEC), enteroinvacive E. coli (EIEC), necrotoxigenic E. coli (NTEC), or the like. It is known that among them, particularly, ETEC generates infectious disease associated with E. coli in swine.

Currently, as a large number of swine are collectively bred in a pork industry, colibacillosis in swine has been in the spotlight as a most frequent and troublesome disease (Non-Patent Document 1). Recently, occurrence of swine colibacillosis has increased in Korea, which has caused growth retardation and death of young swine due to diarrhea, resulting in tremendous economic losses to farmers (Non-Patent Document 2).

In order to prevent and treat colibacillosis in swine, many antibiotics have been administered to swine in the prior art, but when antibiotics has been misused or overused, the misused or overused antibiotics may give rise to drug resistance and remain in bodies of the swine. Therefore, currently, the use of antibiotics has been restricted around the world (Non-Patent Document 3).

Meanwhile, bacteriophage is a specialized type of virus that infects and destroys only bacteria, and can self-replicate only inside host bacteria. The bacteriophage has strong host specificity as compared to antibiotics, and recently, a problem of emergence of strain resistant against antibiotics has been serious, such that an interest in practical use of the bacteriophage has increased (Non-Patent Documents 4 and 5).

Therefore, research into the bacteriophage has been actively conducted in various countries around the world, and in addition to a patent application for bacteriophage, an attempt to acquire Food and Drug Administration (FDA) approval for a composition containing the bacteriophage has been gradually increased.

As the prior art for the bacteriophage, 7 kinds of bacteriophages for controlling E. coli 0157:H have been disclosed in Patent Document 1, and a bacteriophage having a specific bactericidal activity against Staphylococcus aureus has been disclosed in Patent Document 2. Further, lytic protein derived from a bacteriophage specifically destroying a peptidoglycan structure of bacterial cell membrane, and bacteria lysates by the lytic protein have been disclosed in Patent Document 3.

However, in spite of presence of the following prior arts, a technology associated with the bacteriophage for preventing and/or treating infectious diseases by ETEC that are a still important problem in an livestock industry including the pork industry is still insufficient, such that a bacteriophage and a technology associated with the bacteriophage should be developed.

PRIOR ART DOCUMENT Patent Document

-   (Patent Document 1) U.S. Pat. No. 6,485,902 -   (Patent Document 2) Korea Patent Registration No. 10-0910961 B1 -   (Patent Document 3) Korean Patent Laid-Open Publication No.     10-2009-0021475 A

Non-Patent Document

-   (Non-Patent Document 1) Young Il Park, Swine production science,     Sunjin Publishing group, 353-359, 1998 -   (Non-Patent Document 2) Eu Chul Hong, master's thesis, Dankook     University, Addition Effect of Egg Yolk in Early Weaned Piglets,     2001 -   (Non-Patent Document 3) Mason H S et al., Trends in Biotech,     13:388-392, 1995 -   (Non Patent Document 4) Cislo M, et al., Arch. Immunol. Ther. Exp.     2:175-183, 1987 Arch Immunol. Ther. Exp. 2:175-183, 1987 -   (Non Patent Document 5) Sung Hun Kim et al., Bacteriophage, novel     alternative antibiotics, BioWave Vol. 7 No. 15, 2005, BRIC

DISCLOSURE Technical Problem

The present inventors conducted studies in order to solve problems such as resistant bacteria occurring upon the use of antibiotics, antibiotics remaining in meat, and the like, and efficiently prevent and treat infectious diseases by pathogenic E. coli, and as a result, the present inventors isolated new bacteriophage ΦCJ20 (KCCM11362P) having a specific bactericidal activity against ETEC from the nature.

In addition, the present inventors identified morphological, biochemical, and genetic characteristics of the novel bacteriophage and confirmed that the bacteriophage had excellent acid resistance, heat resistance, and the like, thereby developing an antibiotic, a disinfectant, a feed additive, and other compositions using the novel bacteriophage. Further, the present inventors developed a composition for preventing or treating infectious diseases by E. coli, and a method of preventing or treating the disease using the composition.

The present invention provides a novel bacteriophage ΦCJ20 (KCCM11362P) having a specific bactericidal activity against ETEC.

In addition, the present invention provides a composition for preventing and/or treating infectious diseases by ETEC containing the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient.

Further, the present invention provides an antibiotic, a feed additive, a drinking water additive, a disinfectant, or a cleaner containing the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient.

Furthermore, the present invention provides a method of preventing and/or treating infectious diseases by ETEC in animals except for humans using the bacteriophage ΦCJ20 (KCCM11362P) or a composition containing the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient.

Technical Solution

According to an exemplary embodiment of the present invention, there is provided a novel bacteriophage ΦCJ20 (KCCM11362P) having a specific bactericidal activity against enterotoxigenic Escherichia coli (ETEC).

According to another exemplary embodiment of the present invention, there is provided a composition for preventing or treating an infectious disease caused by ETEC, the composition containing the bacteriophage ΦCJ20 (KCCM11362P) as described above as an active ingredient.

According to another exemplary embodiment of the present invention, there are provided an antibiotic, a feed additive, a drinking water additive, a disinfectant, or a cleaner containing the bacteriophage ΦCJ20 (KCCM11362P) as described above as an active ingredient.

According to another exemplary embodiment of the present invention, there is provided a method of preventing or treating an infectious disease caused by ETEC, comprising administering the bacteriophage ΦCJ20 (KCCM11362P), or the composition containing the bacteriophage ΦCJ20 as described above as an active ingredient to animals except for humans.

Advantageous Effects

The bacteriophage ΦCJ20 (KCCM11362P) according to the present invention has an effect of specifically killing enterotoxigenic Escherichia coli (ETEC).

In addition, the bacteriophage ΦCJ20 (KCCM11362P) according to the present invention has excellent acid resistance and heat resistance, such that the bacteriophage ΦCJ20 (KCCM11362P) may be used as a material for preventing or treating infectious diseases by ETEC in various temperature or pH ranges and utilized as an antibiotic, a feed additive, a drinking water additive, a disinfectant, a cleaner, or the like.

Further, according to the present invention, infectious diseases by ETEC may be prevented or treated by administering the bacteriophage ΦCJ20 (KCCM11362P) or a composition containing the bacteriophage ΦCJ20 (KCCM11362P) as an active ingredient to animals except for humans.

DESCRIPTION OF DRAWINGS

FIG. 1 is an electron microscope photograph of a novel bacteriophage ΦCJ20 (KCCM11362P, hereinafter, referred to as ‘ΦCJ20’).

FIG. 2 shows a result of pulsed field gel electrophoresis (PFGE) of the novel bacteriophage ΦCJ20.

FIG. 3 shows a sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) result of the novel bacteriophage ΦCJ20.

FIG. 4 is a graph showing a result of an acid resistance test of the novel bacteriophage ΦCJ20.

FIG. 5 is a graph showing a result of a heat resistance test of the novel bacteriophage ΦCJ20.

BEST MODE

Hereinafter, the present invention will be described in detail. Since contents that are not described in the present specification may be sufficiently recognized and inferred by those skilled in the art or similar art, a description thereof will be omitted.

In detail, one general aspect, the present invention provides a novel bacteriophage ΦCJ20 (KCCM11362P) having a specific bactericidal activity against enterotoxigenic Escherichia coli (ETEC).

ETEC, which is a Gram-negative, rod-shaped bacterium, is an aerobic or facultative anaerobic bacterium decomposing lactose or fructose to produce acid and gas. ETEC well grows in a general medium and may grow at about 7 to 48° C., and an optimal growth temperature is about 35 to 37° C. In addition, ETEC may grow in a pH range of 4.5 to 9.

Since ETEC produces enterotoxins similar to that of Vibrio cholerae, in the case of infection of ETEC, disease symptoms similar to those of cholera are exhibited. The produced toxins are divided into two kinds, that is, a heat-labile enterotoxin (LT) and a heat-stable enterotoxin (ST). The heat-labile enterotoxin means an enterotoxin losing its activity in the case of heating at 60° C. for 10 minutes, and the heat-stable enterotoxin means an enterotoxin that does not lose its activity but has resistance even in the case of heating at 100° C. for 30 minutes.

In the case in which a concentration of ETEC arrives at 10⁷ cfu (colony formation unit) to 10⁸ cfu per a unit volume (1 ml) of serous fluid while ETEC proliferates in an upper portion of intestine, ETEC causes infectious diseases by E. coli such as colibacillosis.

A bacteriophage is a bacteria-specific virus infecting specific bacteria to suppress and inhibit growth of the bacteria and means a virus including single or double stranded deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) as a genetic material.

The bacteriophage ΦCJ20 according to the present invention, which is a bacteriophage species-selectively infecting ETEC, has a structure of isometric capsid but a tail is not observed (FIG. 1), and morphologically belongs to Podoviridae.

The bacteriophage ΦCJ20, which was a bacteriophage newly isolated by the present inventors, was deposited at Korean Culture Center of Microorganisms (361-221, Hongjedong, Seodamun-gu, Seoul, Korea) as a deposition number KCCM11362P on Jan. 30, 2013.

In another general aspect, the present invention provides a composition for preventing or treating infectious diseases by ETEC containing the bacteriophage ΦCJ20 as an active ingredient.

Since the bacteriophage ΦCJ20 has an antibacterial activity capable of specifically killing ETEC, the bacteriophage ΦCJ20 may be used to prevent or treat diseases generated by infection of ETEC. An example of the infectious disease caused by ETEC may include preferably colibacillosis, more preferably colibacillosis in swine, but is not limited thereto.

The term “colibacillosis” as used herein means a disease caused by infection of an animal with pathogenic E. coli, and shows symptoms such as sepsis, diarrhea (neonatal diarrhea and post-weaning diarrhea), toxemia (edema and cerebrospinal angiopathy), or the like. Among them, sepsis is an acute systemic infection that frequently occurs in 2 to 3 days after birth and has a high mortality rate. Diarrhea is the most common outcome of gastrointestinal tract infections that occur during the lactation period within 1-2 weeks after birth and immediately after the weaning period, and causes death or growth retardation Toxemia mainly occurs in 8-12 week-old piglets after the weaning period, and is frequently accompanied by edema and neurologic signs, followed by sudden death.

The term “prevention” as used herein refers to all actions of providing the bacteriophage ΦCJ20 and/or the composition containing the bacteriophage ΦCJ20 as the active ingredient to animals except for humans to suppress the corresponding disease or retard disease occurring.

The term “treatment” as used herein refers to all actions of providing the bacteriophage ΦCJ20 and/or the composition containing the bacteriophage ΦCJ20 as the active ingredient to animals except for humans to thereby allow the symptom of the corresponding disease caused by infection to get better or be alleviated.

The composition for preventing or treating the infectious disease caused by ETEC according to the present invention may contain the bacteriophage ΦCJ20 in an amount of preferably 5×10² to 5×10¹² pfu/ml, more preferably, 1×10⁶ to 1×10¹⁰ pfu/ml.

The composition for preventing or treating the infectious disease caused by ETEC according to the present invention may further contain a pharmaceutically acceptable carrier and be formulated together with the carrier to thereby be provided as food, a drug, a feed additive, a drinking water additive, and the like. The term ‘Pharmaceutically acceptable carrier’ as used herein means a carrier or a diluent that does not stimulate living organism nor inhibit biological activity and properties of an administered compound.

A kind of carrier usable in the present invention is not particularly limited, and any carrier may be used as long as it is generally used in the art and is pharmaceutically acceptable. As a non-restrictive example of the carrier, there are normal saline, sterile water, buffered saline, Ringer's solution, an albumin injection solution, a dextrose solution, a maltodextrin solution, glycerol, ethanol, and the like. One or a mixture of at least two of these carriers may be used.

In addition, if necessary, another general additive such as an antioxidant, a buffer, a bacteriostatic agent, and/or the like, may be further added and used, and the composition may be formulated into an injection formulation such as an aqueous solution, suspension, emulsion, or the like, pills, capsules, granules, tablets, or the like by additionally adding a diluent, a dispersant, a surfactant, a binder, a lubricant, and/or the like, and then used.

An administration method of the composition for preventing or treating infectious diseases by ETEC is not particularly limited, but any method generally used in the art may be used. As a non-restrictive example of the administration method, the composition may be orally or parenterally administered.

As a non-restrictive example of the formulation for oral administration, there are troches, lozenge, tablets, aqueous suspensions, oily suspensions, prepared powder, granules, emulsions, hard capsules, soft capsules, syrups, elixirs, or the like.

In order to formulate the composition according to the present invention into a formulation such as a tablet, a capsule, or the like, the formulation may further contain a binder such as lactose, saccharose, sorbitol, mannitol, starch, amylopectin, cellulose, gelatin; an excipient such as dicalcium phosphate, or the like; a disintegrant such as corn starch, sweet potato starch, or the like; a lubricant such as magnesium stearate, calcium stearate, sodium stearyl fumarate, polyethylene glycol wax, or the like. In the case of the capsule formulation, the formulation may additionally contain a liquid carrier such as fatty oil in addition to the above-mentioned materials.

As a parenteral administration method, an intravenous administration method, an intraperitoneal administration method, an intramuscular administration method, a subcutaneous administration method, a local administration method, or the like, may be used. In addition, a method of applying or spraying the composition onto a disease site may also be used, but the present invention is not limited thereto.

An example of the formulation for parenteral administration may include injection formulations for subcutaneous injection, intravenous injection, intramuscular injection, or the like; suppository formulations; spray formulations such as aerosol formulations capable of being inhaled through respiratory system, or the like, but the present invention is not limited thereto. In order to formulate the composition into the injection formulation, the composition according to the present invention may be mixed with a stabilizer or a buffer in water to thereby prepare a solution or suspension, and then, the prepared solution or suspension may be formulated in a unit dose for an ampoule or vial. In the case of formulating the composition into the spray formulation such as the aerosol formulation, or the like, a propellant, or the like, may be mixed together with an additive so that a water-dispersed condensate or wet powder is dispersed.

A suitable application, spray, or administration dose of the composition for preventing or treating infectious diseases by ETEC may be variously determined depending on factors such as age, weight, sex, degree of symptom of disease, a kind of food, excretion rate of administration target animals, or the like, as well as a method of formulating the composition, an administration method, an administration time and/or route. Generally, a veterinarian having ordinary skill in the art may easily determine and prescribe an effective dose for the desired treatment.

In another general aspect, the present invention may provide an antibiotic containing the bacteriophage ΦCJ20 as an active ingredient.

The term ‘antibiotic’ as used herein means an agent capable of being provided to animals including humans in a drug form to thereby kill bacteria, and corresponds to a concept collectively indicating a preservative, a disinfectant, and an antibacterial agent.

The antibiotic containing the bacteriophage ΦCJ20 according to the present invention as the active ingredient may have high specificity to ETEC as compared to an antibiotic according to the prior art to thereby not kill beneficial bacteria but kill specific pathogenic bacteria, and does not induce drug resistance, such that the antibiotic according to the present invention may be provided as a novel antibiotic having an elongated lifespan as compared to the antibiotic according to the prior art.

In another general aspect, the present invention may provide a feed additive or a drinking water additive containing the bacteriophage ΦCJ20 as an active ingredient.

The feed additive and the drinking water additive according to the present invention may be used in a manner in which the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 is individually prepared in a feed additive or drinking water additive form and then mixed with a feed or drinking water, or in a manner in which the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 is directly added at the time of preparing the feed or the drinking water.

The bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 used as the feed additive or drinking water additive according to the present invention may be in a liquid state or dried state, and preferably, in a dried powder form.

A drying method for preparing the feed additive and the drinking water additive according to the present invention in the dried powder form is not particularly limited, but a method generally used in the art may be used. As a non-restrictive example of the drying method, there is a natural air drying method, natural drying method, a spray drying method, a freeze-drying method, or the like. One method of these methods may be used alone or at least two methods may be used together with each other.

Another non-pathogenic microbe may be additionally added to the feed additive or drinking water additive. A non-restrictive example of the microbe capable of being added may be selected from a group consisting of bacillus sp. capable of producing protease, lipase, and/or sugar converting enzyme such as bacillus subtilis, or the like; Lactobacillus sp. having physiological activity and degradation activity for an organic material under anaerobic conditions such as cow's stomach; mold fungi having effects of increasing a weight of domestic animal, a milk yield, and digestibility of the feed such as Aspergillus oryzae, or the like; and yeasts such as Saccharomyces cerevisiae, or the like. One or a mixture of at least two of these microbes may be used.

The feed additive or the drinking water additive containing the bacteriophage ΦCJ20 according to the present invention as the active ingredient may further contain other additives, as needed. As a non-restrictive example of the usable additive, there are a binder, an emulsifier, a preservative, and the like, which are added in order to prevent quality of the feed or driving water from being deteriorated; amino acids, vitamins, enzymes, probiotics, flavoring agents, non-protein nitrogen compounds, silicates, buffers, coloring agents, extractants, oligosaccharides, and the like, which are added in order to increase utility of the feed or drinking water. Otherwise, the additive may further include a feed mixing agent, or the like. One or a mixture of at least two of these additives may be used.

The feed additive may be contained at a content of 0.05 to 10, more preferably 0.1 to 2 parts by weight based on 100 parts by weight of the feed. The drinking water additive may be contained at a content of 0.0001 to 0.01, more preferably 0.001 to 0.005 parts by weight based on 100 parts by weight of the drinking water. The activity of the bacteriophage ΦCJ20 against ETEC may be sufficiently exhibited in the above-mentioned range.

In another general aspect, the present invention provides a feed or drinking water prepared by adding a feed additive or a drinking water additive containing the bacteriophage ΦCJ20 as an active ingredient or directly adding the bacteriophage ΦCJ20.

The feed used in the present invention is not particularly limited, but any feed generally used in the art may be used. A non-restrictive example of the feed may include plant feeds such as grains, roots and fruit, food processing byproducts, algaes, fiber, pharmaceutical byproducts, fats, starches, cucurbitaceous, or grain byproducts; and animal feeds such as proteins, inorganic materials, fats, minerals, single cell proteins, animal planktons, or foods. One or a mixture of at least two of these feeds may be used.

The drinking water used in the present invention is not particularly limited, but any drinking water generally used in the present invention may be used.

In another general aspect, the present invention may provide a disinfectant or a cleaner containing the bacteriophage ΦCJ20 as an active ingredient. A formulation of the disinfectant or cleaner is not particularly limited, but the disinfectant or cleaner may be formulated into any formulation known in the art.

The disinfectant may be sprayed in order to remove ETEC onto a region in which animals live, a slaughterhouse, a mortality generation area, a cooking place or cooking equipment, or the like, but the present invention is not limited thereto.

The cleaner may be used to wash skin's surfaces or each of the sites of bodies of animals exposed or to be exposed to ETEC, but the present invention is not limited thereto.

In another general aspect, the present invention provides a method of preventing or treating infectious diseases by using the bacteriophage ΦCJ20 or the composition comprising the bacteriophage ΦCJ20 as an active ingredient.

In detail, the method of preventing or treating infectious diseases according to the present invention may include administering the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 as the active ingredient to targets infected by ETEC or being at risk of infection of ETEC except for humans in a pharmaceutically effective dose. It will be apparent to those skilled in the art that when the pharmaceutical composition is administered to patient, the suitable total daily dose may be determined by an attending physician or veterinarian within the scope of sound medical judgement.

A specific pharmaceutically effective dose of the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 as the active ingredient for a specific animal may be determined by considering an administration time and an administration route of the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20, a secretion rate of the composition, a therapy duration period, or the like, in addition to a kind and a degree of the desired response, an age, a weight, a general healthy state, sex, or diet of the corresponding individual. In addition, the pharmaceutically effective dose may be variously changed according to various factors such as ingredients of drugs or other compositions simultaneously or separately used and similar factors well known in a medical field.

The bacteriophage ΦCJ20 according to the present invention or the composition containing the bacteriophage ΦCJ20 as the active ingredient may be administered as a pharmaceutical form (nasal spray) to animals or administered in a method of directly added to a feed or drinking water of the animals and then feeding the feed or drinking water. In addition, the bacteriophage ΦCJ20 or the composition containing the same may be mixed in a feed or drinking water in a form of a feed additive or drinking water additive and then administered.

The administration route and administration method of the bacteriophage ΦCJ20 according to the present invention or the composition containing the bacteriophage ΦCJ20 as the active ingredient are not particularly limited, but any administration route and administration method may be used as long as the bacteriophage ΦCJ20 or the composition containing the same may arrive at the corresponding target tissue. That is, the bacteriophage ΦCJ20 or the composition containing the bacteriophage ΦCJ20 as the active ingredient may be administered through various oral or parenteral routes. As a non-restrictive example of the administration route, oral, rectal, local, intravenous, intraperitoneal, intramuscular, intraarterial, subcutaneous, and nasal administration, inhalation, or the like, may be performed.

Hereinafter, the present invention will be described in detail through the Examples. However, these Examples are only to illustrate the present invention, and a scope of the present invention is not limited to these Examples.

Example 1 Isolation of Bacteriophage Infecting ETEC Example 1-1 Screening of Bacteriophage and Isolation of Single Bacteriophage

After 50 ml of a sample obtained from pig feces and environmental samples of Samwhaw Gps. Breeding Agri. in Gwangcheon area, Hong seong-gun, Chungchong Province was centrifuged at 4,000 rpm for 10 minutes, the supernatant was filtered with a 0.45 μm filter to prepare a sample solution, and then a soft agar overlay method was performed using the prepared sample solution. The soft agar overlay method is a method of observing a lysis action of bacteriophage using host cells growing in top agar (attached onto a solid medium using 0.7% agar).

In detail, 18 ml of the sample filtrates was mixed with 150 μl of a shake culture solution (OD₆₀₀=2) of ETEC (SNU105) obtained from College of Veterinary Medicine, Seoul National University and 2 ml of 10× Luria Bertani (LB) medium (tryptone 10 g/l; yeast extract 5 g/l; and NaCl 10 g/l) and cultured at 30° C. for 18 hours. Then, the culture solution was centrifuged at 4,000 rpm for 10 minutes, and the supernatant was filtered with a 0.45 μm filter. Then, after a mixed solution of 3 ml of 0.7%(w/v) agar and 150 μl of the shake culture solution (OD₆₀₀=2) of ETEC (SNU105) was poured and hardened onto a LB plate medium, 10 μl of the sample solution was dropped thereon, followed by culturing at 30° C. for 18 hours. Then, it was confirmed that a plaque was formed.

Since it is known that one kind of bacteriophage is present in a single plaque, separation of a single bacteriophage from the formed plaque was attempted. In detail, the plaque was added to 400 μl of a SM solution (NaCl (5.8 g/l); MgSO₄7H₂O (2 g/l); 1M Tris-Cl (pH 7.5, 50 ml)) and left at room temperature for 4 hours, thereby obtaining a bacteriophage solution. Thereafter, 100 μl of the bacteriophage solution was mixed with 5 ml of 0.7%(w/v) agar and 150 μl of the shake culture solution (OD₆₀₀=2) of ETEC (SNU105), followed by performing the soft agar overlay method using a LB medium having a diameter of 150 m. The culturing was performed until ETEC was completely lysed. After the culturing was terminated, 5 ml of the SM solution was added to the LB plate medium and left at room temperature for 4 hours, thereby obtaining a bacteriophage solution.

After the solution was recovered and 1% (v/v) chloroform was added thereto, the mixture was mixed for 10 minutes, followed by centrifugation at 4,000 rpm for 10 minutes, thereby obtaining a supernatant. The obtained supernatant was filtered with a 0.45 μm filter, thereby obtaining a final sample.

Examples 1-2 Large-Scale Culture and Purification of Bacteriophage

The bacteriophage obtained in Example 1-1 was cultured at large scale using ETEC (SNU105), and then the bacteriophage was purified therefrom.

In detail, after ETEC (SNU105) was shake-cultured, and an aliquot of 1.5×10¹⁰ cfu was centrifuged at 400 μl rpm for 10 minutes and then resuspended in 4 μl of the SM solution. The bacteriophage of 1.5×10⁶ pfu was inoculated thereto (multiplicity of infection (MOI)=0.0001), and left at room temperature for 20 minutes. Thereafter, the solution was inoculated into 150 ml of the LB medium and cultured at 30° C. for 5 hours.

After the culturing was terminated, chloroform was added at an amount of 1% (v/v) of a final volume and stirred for 20 minutes. Then, restriction enzymes DNase I and RNase A were added so as to have a final concentration of 1 μg/ml, respectively, and the solution was left at 30° C. for 30 minutes. Then, NaCl and polyethylene glycol (PEG) were added so as to have final concentrations of 1M and 10% (w/v), respectively, and further left at 4° C. for 3 hours, followed by centrifugation at 4° C. and 12,000 rpm for 20 minutes, thereby obtaining precipitates.

The obtained precipitate was suspended in 5 ml of a SM solution and left at room temperature for 20 minutes. Then, 1 ml of chloroform was added thereto and stirred, followed by centrifugation at 4° C. and 4,000 rpm for 20 minutes, thereby obtaining a supernatant. Thereafter, the supernatant was filtered with a 0.45 μm filter, and ultracentrifugation (35,000 rpm, 1 hour, 4° C.) using a glycerol density gradient method (density: 40%, 5% glycerol) was performed, thereby purifying the bacteriophage.

The present inventor designated the bacteriophage obtained by extracting the sample from pig feces and having the specific bacteriocidal activity against ETEC as “Bacteriophage ΦCJ20” and deposited the bacteriophage at Korean Culture Center of Microorganisms (361-221, Hongjedong, Seodamun-gu, Seoul, Korea) as a deposition number KCCM11362P on Jan. 30, 2013.

Example 2 Examination of ΦCJ20 infection on E. coli

In order to confirm whether or not the bacteriophage ΦCJ20 purified in Example 1 has a lytic activity on E. coli species other than ETEC (SNU105), cross infection with other E. coli species was performed.

In detail, 2 kinds of ETEC (SNUJG280 and SNU105) strains and 11 kinds of non-pathogenic E. coli strains (MC4100, BL21(DE3), Rosetta(DE3), 2616, 281, 1917, DH5a, GM2929, Tuner(DE3), W3110, and K12G) were cultured, thereby obtaining culture solutions, respectively. Then, each of the culture solutions and the purified bacteriophage ΦCJ20 were used to perform the soft agar overlay method, and whether or not a plaque was formed was confirmed.

The results were shown in the following Table 1.

TABLE 1 Serotype) strain Plaque formation Non-pathogenic MC4100 ∘ E. coli BL21(DE3) ∘ Rosetta(DE3) ∘ 2616 x 281 x 1917 ∘ DH5a ∘ GM2929 ∘ Turner ∘ W3110 ∘ K12G ∘ ETEC SNUJG280 ∘ SNU105 ∘

As shown in Table 1, it may be confirmed that the bacteriophage ΦCJ20 purified in Example 1 had the lytic activity on 9 kinds of non-pathogenic E. coli strains (MC4100, BL21(DE3), Rosetta(DE3), 1917, DH5a, GM2929, Tuner(DE3), W3110, and K12G) but did not have lytic activity on the residual 2 kinds of non-pathogenic E. coli strains (2616 and 281) among the non-pathogenic E. coli strains.

Example 3 Observation of Morphology of ΦCJ20

The bacteriophage ΦCJ20 purified in Example 1 was diluted in a 0.01% gelatin solution, and then fixed in a 2.5% glutaraldehyde solution. The fixed bacteriophage was dropped onto a carbon-coated mica plate (ca. 2.5×2.5 mm), adapted thereto for 10 minutes, and washed with sterile distilled water. A carbon film was mounted on a copper grid, stained with 2% uranyl acetate for 30 to 60 seconds, dried, and investigated using a transmission electron microscope (JEM-1011, 80 kV, magnification: ×120,000 to ×200,000) (FIG. 1).

FIG. 1 is an electron microscopy photograph of the bacteriophage ΦCJ20. It may be appreciated that the bacteriophage ΦCJ20 has an isometric capsid but does not have a tail, such that the bacteriophage ΦCJ20 morphologically belongs to Podoviridae.

Example 4 Genomic DNA Size Analysis of ΦCJ20

Genomic DNA was extracted from the bacteriophage ΦCJ20 purified in Example 1.

In detail, 20 mM ethylenediaminetetraacetic acid (EDTA), 50 μg/ml proteinase K, and 0.5% (w/v) sodium dodecyl sulfate (SDS) were added to a culture solution of the purified bacteriophage ΦCJ20 and left at 50° C. for 1 hour. An equal volume of phenol (pH 8.0) was added and stirred, followed by centrifugation at room temperature and 12,000 rpm for 10 minutes, thereby obtaining a supernatant.

The supernatant was mixed with an equal volume of PC (phenol:chloroform=1:1) and centrifuged at room temperature and 12,000 rpm for 10 minutes, thereby obtaining a supernatant. The supernatant was mixed with an equal volume of chloroform and centrifuged at room temperature and 12,000 rpm for 10 minutes, thereby obtaining a supernatant. The obtained supernatant was sequentially mixed with 10% (v/v) of 3M sodium acetate and a double volume of cold 95% ethanol, based on the total volume, and left at −20° C. for 1 hour. Subsequently, centrifugation was performed at 0° C. and 12,000 rpm for 10 minutes, and the precipitate was obtained by removing the supernatant. Then, 50 μl of Tris-EDTA (TE) buffer (pH 8.0) was added thereto to thereby dissolve the obtained precipitate. The extracted DNA was diluted 10 times, and a concentration was measured by measuring absorbance at OD₂₆₀.

Next, 1 μg of DNA was loaded onto 1% pulse-field gel electrophoresis (PFGE) agarose gel, and electrophoresis was performed at room temperature for 20 hours using a BIORAD PFGE system program 7 (size range: 25-100 kb; switch time ramp: 0.4-2.0 seconds, linear shape; forward voltage: 180 V; reverse voltage: 120 V) (FIG. 2).

FIG. 2 is a pulsed field gel electrophoresis (PFGE) photograph of the genomic DNA of the bacteriophage ΦCJ20, and it may be confirmed that the genomic DNA of the bacteriophage ΦCJ20 has a size of about 40 kb. In FIG. 2, M is DNA that becomes a standard for measuring a molecular weight.

Example 5 Protein Pattern Analysis of ΦCJ20

15 μl of purified bacteriophage ΦCJ20 solution at a titer of 10¹⁰ pfu/ml was mixed with 3 μl of a 5×SDS sample solution, and heated for 5 minutes. Then, 12% SDS-PAGE was performed (FIG. 3).

FIG. 3 is an electrophoresis photograph showing a result of SDS-PAGE performed on the bacteriophage ΦCJ20, and main proteins having sizes of about 46.5 kDa, 43 kDa, 39.5 kDa, and 17.1 kDa were observed.

Example 6 Genetic Characteristics Analysis of ΦCJ20

In order to confirm genetic characteristics of the bacteriophage ΦCJ20 purified in Example 1, DNA of the bacteriophage ΦCJ20 was analyzed using a FLX titanium sequencer (Roche), which is a gene analysis apparatus. Genes was assembled at Macrogen INC. using GS and de novo assembler software (Roche). Sequence analysis of an open reading frame was performed using GeneMArk.hmm, Glimmer v3.02, and FGENESB software. Identification of the open reading frame was performed using BLASTP and InterProScan program.

The genome sequence of the bacteriophage had various similarities with that of the existing reported bacteriophage, but it was confirmed that a bacteriophage of which all of the fractions were completely (100%) equal to those of the bacteriophage of the present invention did not exist. Therefore, it may be confirmed that the bacteriophage was a newly isolated bacteriophage.

The following Table 2 shows results obtained by comparing homologues of the genome sequence of the ΦCJ20 and decoded genome sequences of other bacteriophages, and partial genome sequence of the ΦCJ20 was shown below.

TABLE 2 Query Subject score Identities Name Length Start End Description E-Value Match/Total Pct.(%) contig00001_orf00002 354 1 351 PseT.3 conserved hypothetical 5E-42 110/117 94 protein [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00004 489 7 486 hypothetical protein VR7_gp239 2E-82 152/160 95 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00038 933 1 930 basseplate tail tube initiator 4E-172 309/310 99 [Shigella phage SP18] contig00001_orf00047 465 1 462 UvsY recombination repair and 1E-82 152/154 98 ssDNA binding protein [Shigella phage SP18] contig00001_orf00072 492 1 489 small terminase protein 1E-77 162/163 99 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00074 801 1 798 gp15 tail sheath stabilizer and 1E-142 264/266 99 completion protein [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00066 261 1 135 prohead core protein precursor to 1E-16  45/45 100 internal peptides [Shigela phage SP18] contig00001_orf00076 939 1 936 gp13 neck protein 3E-159 308/312 98 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00093 456 1 453 57B conserved hypothetical 3E-82 150/151 99 protein [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00087 603 1 600 gp53 baseplate wedge subunit 2E-112 192/200 96 [Enterobacteria phage vB_EcoM-VR7] contig00002_orf00005 456 1 453 lysozyme [Enterobacteria phage 4E-81 143/151 94 T7] contig00002_orf00007 699 1 633 gp2.5 [Enterobacteria phage 13a] 4E-105 208/211 98 contig00002_orf00011 309 1 300 gp1.7 [Enterobacteria phage 285P] 1E-47  92/102 90 contig00002_orf00035 1032 1 996 gp10A [Enterobacteria phage 13a] 1E-137 313/333 93 contig00003_orf00016 363 1 360 hypothetical protein SP18gp253 3E-62 117/120 97 [Shigella phage SP18] contig00001_orf00056 1008 1 1005 RNA ligase 2 [Shigella phage 6E-172 321/335 95 SP18] contig00001_orf00101 390 10 387 hypothetical phage protein 6E-66 120/126 95 [Escherichia phage wV7] contig00001_orf00089 825 1 822 gp2 DNA end protector protein 7E-147 273/274 99 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00019 348 1 345 head assembly cochaperone with 2E-51 115/115 100 GroEL [Shigella phage SP18] contig00001_orf00008 906 1 903 polynucleotide 5′-kinase and 3′- 1E-170 287/301 95 phosphatase [Shigella phage SP18] contig00001_orf00006 321 1 318 hypothetical protein EpJS10_0215 2E-50 102/106 96 [Enterobacteria phage JS10] contig00001_orf00020 324 1 321 lysis inhibition accessory protein 5E-53 105/107 98 rapid lysis phenotype [Shigella phage SP18] contig00001_orf00017 582 1 579 deoxycytidylate deaminase 6E-111 191/193 98 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00081 870 1 867 baseplate wedge tail fiber 5E-161 286/289 98 connector [Shigella phage SP18] contig00001_orf00013 360 1 357 hypothetical protein SP18gp231 2E-47 113/119 94 [Shigella phage SP18] contig00001_orf00037 324 1 321 hypothetical protein SP18gp210 3E-51 104/107 97 [Shigella phage SP18] contig00001_orf00079 666 1 663 baseplate wedge subunit and tail 2E-118 215/221 97 pin [Shigella phage SP18] contig00002_orf00043 903 1 900 exonuclease [Enterobacteria 6E-168 293/300 97 phage T7] contig00003_orf00017 912 7 876 single stranded DNA binding 6E-145 287/290 98 protein [Shigella phage SP18] contig00001_orf00063 819 1 816 prohead core protein 5E-99 267/272 98 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00044 729 1 726 baseplate hub assembly catalyst 2E-128 241/242 99 [Shigella phage SP18] contig00001_orf00088 354 1 351 head completion protein 2E-64 115/117 98 [Shigella phage SP18] contig00001_orf00023 369 1 366 hypothetical protein SP18gp221 4E-66 122/122 100 [Shigella phage SP18] contig00001_orf00046 390 1 387 baseplate wedge subunit 5E-66 128/129 99 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00053 849 1 846 head outer capsid protein 3E-141 268/282 95 [Shigella phage SP18] contig00001_orf00042 459 1 456 gp28 baseplate hub distal subunit 3E-83 150/152 96 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00064 639 1 636 prohead core scaffold protein and 4E-118 210/212 99 protease [Shigella phage SP18] contig00001_orf00052 669 1 666 inhibitor of prohead protease gp21 2E-91 206/222 92 [Shigella phage SP18] contig00001_orf00045 624 1 621 baseplate hub subunit 4E-115 206/207 99 [Shigella phage SP18] contig00001_orf00086 1788 1 1785 baseplate hub subunit and tail 0 588/595 98 lysozyme [Shigella phage SP18] contig00001_orf00094 366 1 363 hypothetical protein VR7_gp156 2E-48 119/121 98 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00016 336 1 333 hypothetical protein SP18gp229 2E-54 108/111 97 [Shigella phage SP18] contig00002_orf00001 408 1 405 4.7 protein [Enterobacteria phage 2E-54 123/135 91 T7] contig00002_orf00013 1023 1 1020 DNA ligase [Enterobacteria phage 0 317/359 88 T7] contig00002_orf00027 1500 1 975 gp17 [Enterobacteria phage 6E-120 268/330 81 13a] contig00002_orf00033 591 1 586 tail protein [Yersinia pestis phage 2E-99 194/196 98 phiA1122] contig00003_orf00003 411 1 408 endonuclease II [Shigella phage 5E-72 135/136 100 SP18] contig00003_orf00008 861 1 858 dTMP thymidylate synthase 2E-146 245/286 85 [Enterobacteria phage vB_EcoM-VR7] contig00003_orf00019 669 1 648 loader of gp41 DNA helicase 4E-118 211/216 97 [Shigella phage SP18] contig00001_orf00110 306 1 303 hypothetical protein SP18gp146 4E-50  99/101 96 [Shigella phage SP18] contig00001_orf00058 1281 1 1278 capsid vertex protein 0 411/426 96 [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00041 1746 1 1743 baseplate hub subunit tail lenght 0 570/581 98 determinator [Shigella phage SP18] contig00001_orf00064 1959 1 1956 baseplate wedge subunit 0 648/652 99 [Shigella phage SP18] contig00001_orf00080 1785 1 1782 gp10 baseplate wedge subunit 0 583/594 98 and tail pin [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00040 1095 1 1092 baseplate tail tube cap 0 362/364 99 [Shigella phage SP18] contig00001_orf00090 600 1 597 gp3 tail completion and sheath 2E-112 199/199 100 stabilized protein [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00068 492 1 489 tail tube protein 2E-93 161/163 98 [Shigella phage SP18] contig00001_orf00091 678 1 675 gp1 deoxynucleoside 2E-127 222/225 98 monophosphate kinase [Enterobacteria phage vB_EcoM-VR7] contig00001_orf00032 717 1 714 hypothetical protein SP18gp215 3E-128 235/238 98 [Shigella phage SP18] contig00001_orf00025 366 1 363 hypothetical protein SP18gp220 1E-66 120/121 99 [Shigella phage SP18] contig00001_orf00001 405 1 402 inhibitor of host transcription 2E-61 131/134 97 [Shigella phage SP18] contig00001_orf00112 594 1 591 hypothetical protein SP18gp145 7E-100 193/197 97 [Shigella phage SP18] contig00001_orf00076 786 1 753 neck protein 1E-144 251/251 100 [Enterobacteria phage vB_EcoM-VR7] contig00002_orf00006 458 1 453 gp3 [Enterobacteria phage 13a] 1E-82 149/151 98 contig00002_orf00017 1080 1 1077 protein kinase [Enterobacteria 2E-163 325/359 90 phage T7] contig00002_orf00024 360 1 357 gp16.5 [Enterobacteria phage 13a] 1E-57 112/119 94 contig00002_orf00030 591 1 588 internal virion protein [Yersinia 1E-74 178/195 90 pestis phage phiA1122] contig00003_orf00009 582 1 579 Frd dihydrofolate reductase 6E-105 187/193 96 [Enterobacteria phage vB_EcoM-VR7] contig00003_orf00011 342 1 339 hypothetical protein SP18gp249 3E-59 111/113 98 [Shigella phage SP18] contig00003_orf00014 366 1 363 hypothetical protein SP18gp252 2E-60 119/121 93 [Shigella phage SP18] please see the [partial genome Sequence of ΦCJ20] in attachment.

Example 7 Stability Test of ΦCJ20 Depending on pH

In order to confirm whether or not the bacteriophage ΦCJ20 may have stability in a low pH environment in stomach, stability test was performed over a wide pH range (pH 3.0, 3.5, 4.0, 5.5, 6.4, 7.5, 8.3, 9.2, and 11.0).

For test, various pH solutions (sodium acetate buffer (pH 4.0, pH 5.5, and pH 6.4), sodium citrate buffer (pH 3.0 and pH 3.5), sodium phosphate buffer (pH 6.9 and pH 7.4), and Tris-HCl solution (pH 8.2, pH 9.0, pH 9.8, and pH 11.0)) were prepared at a concentration of 0.2 M, respectively.

After 180 μl of each of the pH solutions was mixed with 20 μl of bacteriophage solution having a titer of 2.1×10¹⁰ pfu/ml so that a concentration of each of pH solution became 1 M, and each of the pH solutions was left at room temperature for 2 hours. In a control group, 20 μl of the bacteriophage solution (2.1×10¹⁰ pfu/ml was mixed with 180 μl of SM solution and then left at room temperature for 2 hours. Then, the reaction solution was diluted step by step, 10 μl of the diluted solution at each step was dropped and cultured at 30° C. for 18 hours by a soft agar overlay method, and the titer was measured through the presence or absence of lysis (FIG. 4).

FIG. 4 shows a result of the acid resistance test of the bacteriophage ΦCJ20. As shown in FIG. 4, it may be confirmed that the bacteriophage ΦCJ20 did not lose its activity and was stable in a pH range of 5.0 to 11.0 as compared to the control group.

Example 8 Stability Test of ΦCJ20 Depending on Temperature

A test for confirming stability against heat generated during a formulating process of the bacteriophage in the case of using the bacteriophage as a feed additive formulation among formulations of the bacteriophage was performed.

In detail, 100 μl of bacteriophage ΦCJ20 solution having a concentration of 2.0×10¹⁰ pfu/ml was left at 37° C., 42° C., 53° C., and 60° C. for 0, 30, 60, and 120 minutes, respectively. Then, the solutions above were diluted step by step, 10 μl of the diluted solution at each of the steps was dropped and cultured at 30° C. for 18 hours by a soft agar overlay method, and the titer was measured through the presence or absence of lysis (FIG. 5).

FIG. 5 shows a result of a heat resistance test of the bacteriophage ΦCJ20. As shown in FIG. 5, the bacteriophage ΦCJ20 maintained its activity even though exposed at 53° C. for up to 2 hours, but its activity was reduced according to the exposure time, when exposed at 60° C.

Example 9 Infection Spectrum Test of ΦCJ20 on Wild-Type Strains of ETEC

Whether or not the bacteriophage ΦCJ20 had a lytic activity was tested on 15 wild-type strains of ETEC obtained from College of Veterinary Medicine, Seoul National University and University of Guelph in Canada other than ETEC (SNU105) used in the experiment.

In detail, 10 μl of bacteriophage ΦCJ20 solution having a titer of 10⁹ pfu/ml and mixed with 150 μl of a shake culture solution (OD₆₀₀=2) of each of the strains was dropped and cultured at 30° C. for 18 hours by a soft agar overlay method. Then, whether or not a plaque was formed was observed.

The results were shown in the following Table 3.

TABLE 3 Serotype Strain Plaque formation ETEC SNU345 x SNU105 ∘ SNU0122 x SNU0149 ∘ SNUJG280 ∘ SNUF4 ∘ SNU162 ∘ SNU160 ∘ SNU107 ∘ CANR08 ∘ SNU2618 x SNU2617 x SNU193 x SNU274 ∘ SNU3220 ∘

As shown in Table 3, the bacteriophage showed infectivity on F-serotype K88 (SNU105, SNU107, SNU160, SNU162, SNUF4, SNU3220, CANR08, and SNUJG280) as well as ETEC 0-serotype 0149 (SNU107, SNUF4, SNUJG280, SNU3220, CANR08, and SNU0149) which is the most common cause of diarrhea in swine in general farms. Therefore, it may be expected that the bacteriophage will show excellent efficiency at the time of actually applying the bacteriophage. 

1. A novel bacteriophage ΦCJ20 (KCCM11362P) having a specific bactericidal activity against enterotoxigenic Escherichia coli (ETEC).
 2. A composition for preventing or treating an infectious disease caused by ETEC, comprising the bacteriophage ΦCJ20 (KCCM11362P) of claim 1 as an active ingredient.
 3. The composition according to claim 2, wherein the infectious disease is colibacillosis.
 4. An antibiotic comprising the bacteriophage ΦCJ20 (KCCM11362P) of claim 1 as an active ingredient.
 5. A feed additive or drinking water additive comprising the bacteriophage ΦCJ20 (KCCM11362P) of claim 1 as an active ingredient.
 6. A disinfectant or cleaner comprising the bacteriophage ΦCJ20 (KCCM11362P) of claim 1 as an active ingredient.
 7. A method of preventing or treating an infectious disease caused by ETEC, comprising administering the bacteriophage ΦCJ20 (KCCM11362P) of claim 1 to animals except for humans.
 8. The method according to claim 7, wherein the infectious disease is colibacillosis.
 9. A method of preventing or treating an infectious disease caused by ETEC, comprising administering the composition of claim 2 to animals except for humans.
 10. The method according to claim 9, wherein the infectious disease is colibacillosis. 